Method of reducing fumes from a vessel of molten asphalt

ABSTRACT

A container for asphalt includes a sidewall and a bottom assembled to the sidewall to form the container for holding the asphalt in the container, the bottom thereafter being melted with the asphalt without adversely affecting the asphalt properties.

CROSS-REFERENCE TO RELATED APPLICATIONS

1. This application is a continuation-in-part of copending Serial No. 09/169,964 to Marzari et al., filed Oct. 13, 1998.

TECHNICAL FIELD AND INDUSTRIAL

2. 1. Applicability of the Invention

3. This invention relates in general to asphalt materials for use in roofing, paving and other applications. More particularly, this invention relates to a container and method to produce such a container, for reducing fumes emitted from a vessel of the molten asphalt. The invention can be useful for providing asphalt for use in locations where fumes from the molten asphalt are a concern.

4. 2. Background of the Invention

5. Asphalt from processing and terminalling facilities is transported to end users in one of several ways, including direct piping of molten asphalt to nearby customers, shipping in molten form via tanker truck, railcar and barge, and shipping in solid form in individual packages. The packages are used primarily by building contractors as a source of asphalt for roofing applications. The contractor typically places the solid asphalt in a heated kettle to melt the asphalt for use. Asphalt shipped in molten form is also usually further heated in a kettle prior to use.

6. A problem associated with such heated kettles of molten asphalt is that they can emit significant amounts of fumes. The fumes can be unsightly, and an irritant to workers and others in the surrounding area. Accordingly, it would be desirable to reduce the amount of fumes normally emitted from a kettle or other vessel of molten asphalt.

7. It would also be desirable to reduce fuming and odors without substantial modification of the processed or raw asphalt. By contrast with known polymer-modified asphalt compositions, which are highly modified materials where the polymer is used, e.g., to impart elongation properties, an asphalt without such modification is desired for many applications.

8. It would also be desirable to reduce fuming and odors of molten asphalt while permitting for convenient, user-tailorable enhancement or alteration of the asphalt properties.

9. Furthermore, it would be desirable to produce a low-fuming asphalt in a convenient package. Individual packages of asphalt are typically formed at conventional asphalt processing facilities by pouring molten asphalt into containers made of a metal bottom and paper cylindrical sidewalls. The asphalt is typically poured at temperatures of about 177° C. and the packages are allowed to cool for up to 24 hours prior to shipping.

10. A problem with existing asphalt packages is that removal of the paper and metal container from the solid asphalt is time-consuming. The disposal of the paper and metal container material is also burdensome. Therefore, it would be desirable to be able to package asphalt in individual packages and yet eliminate the need to remove the container or to dispose of the entire container. In particular, it would be desirable to provide a container for asphalt that is consumable at least in part so that it can be melted right along with the asphalt. Preferably any nonconsumable portion of the container may be removed without the use of a knife, thereby improving the ease and safety of removal.

11. The inventors have found that our previous consumable containers, such as described in U.S. Pat. No. 5,733,616, which is incorporated herein by reference, while providing great utility for the end consumer, caused significant changes to the process of pouring the asphalt into the container, and as such, there exists a need for a container that is more readily adapted to existing facilities.

12. Commonly assigned U.S. Pat. Nos. 6,130,276 and 6,069,194, which are incorporated herein by reference, describe methods of reducing fumes in asphalt. These patents do not describe the improved container as presently envisioned by Applicants.

SUMMARY OF THE INVENTION

13. The above objects as well as other objects not specifically enumerated are achieved by a container, and method of making such a container, for holding asphalt. Such a container comprises cylindrical sides and a bottom, the sides preferably being removed at the jobsite prior to melting the asphalt, while the bottom is melted with the asphalt.

14. A container for asphalt includes a sidewall and a bottom assembled to the sidewall to form the container for holding the asphalt in the container, the bottom thereafter being melted with the asphalt without adversely affecting the asphalt properties. In a preferred embodiment, the consumable bottom provides enough polymer in the melted asphalt, such that the mixture includes about 0.2 weight percent to about 6 weight percent of a polymer to the asphalt to reduce the visual opacity of the fumes by at least about 25% over the same asphalt without the polymer. In another embodiment, the total emissions of benzene soluble suspended particulates is reduced by at least about 15% over the same asphalt without the polymer. Preferably, the added polymer has a melt flow index of from about 4 grams/10 minutes to about 150 grams/10 minutes, and the added polymer reduces the visual opacity of the fumes by forming a skim on the upper surface of the molten asphalt.

BRIEF DESCRIPTION OF THE DRAWINGS

15.FIG. 1 is a schematic view in perspective of a prior art asphalt package, which includes a cylindrical paper carton with a steel bottom, the container being filled with asphalt and solidified, but removed at a jobsite and disposed of in its entirety.

16.FIG. 2 is a schematic view in perspective of one embodiment of an improved asphalt package, which includes a partially consumable container filled with asphalt, useful for reducing fumes and odors from a vessel of the molten asphalt in accordance with the invention.

17.FIG. 3 is a perspective view of a bottom for a partially consumable container as shown in FIG. 2.

18.FIG. 4 is a partial cross-sectional view of one embodiment of the bottom shown in FIG. 2.

19.FIG. 5 is a partial cross-sectional view of an alternative embodiment of the bottom shown in FIG. 2.

20.FIG. 6 is a perspective view of an alternative bottom for a partially consumable container as shown in FIG. 2.

21.FIG. 7 is a partial cross-sectional view of one embodiment of the bottom shown in FIG. 6.

22.FIG. 8 is a cross-sectional view of an alternative embodiment of an improved asphalt package, which includes a partially consumable container filled with asphalt, useful for reducing fumes and odors from a vessel of the molten asphalt in accordance with the invention.

23.FIG. 9 is a schematic view in perspective of a cylindrical carton for use in the embodiment shown in FIG. 8.

24.FIG. 10 is a schematic view in perspective of the cylindrical carton shown in FIG. 9, with the bottom folded.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

25. Commonly assigned U.S. Pat. Nos. 6,130,276 and 6,069,194 describe methods of reducing fumes in asphalt. The inventors have found that it is most convenient for the end user of the asphalt to have the polymer contained in the asphalt package. Furthermore, the inventors have found that removal and disposal of non-consumable containers presents a labor cost to the user, as well as a disposal cost. Accordingly, applicants found that by replacing the bottom of the conventional container with a consumable bottom, the low fuming benefit may be achieved, while reducing the labor and disposal costs of the nonconsumable container (particularly the metal bottom). Thus, after the container bottom melts, some of the polymer rises to the upper surface of the molten asphalt in the vessel to form a skim thereon that reduces fuming, as described in the above-referenced patents. As described therein, the term “skim” means a layer, film, or coating which floats, forms, or collects on the upper surface of the molten asphalt. Preferably, the polymer forms a skim across at least about 80-90% of the upper surface of the molten asphalt, and more preferably across substantially the entire upper surface of the molten asphalt. It is understood that when additional asphalt is placed into the vessel, the skim may be broken but it usually quickly reforms over the surface.

26. While not intending to be limited by theory, it is believed that the skim reduces fuming from the vessel by acting as a cool top or barrier to exposure of the molten asphalt to air. The thickness of the skim is a function of the addition rate of polymer minus the polymer's dissolution rate. The dissolution rate is a function of fundamental polymer properties as well as vessel temperature and agitation level. The thickness of the skim is usually from about 5 mm to about 50 mm, and typically about 15-25 mm. However, it is believed that a skim thickness of at least about 0.025 mm, more preferably at least about 0.25 mm, is suitable for reducing fuming from the vessel.

27. The inclusion of polymers to form such skims may advantageously be used with any asphalt product that is generally heated in an open kettle in preparation for its use. As used herein the term “asphalt” is meant to include asphalt bottoms from petroleum refineries, as well as naturally occurring bituminous materials such as asphalts, gilsonite, tars, and pitches, or these same materials that have been air-blown or otherwise chemically processed or treated. For example, the asphalt can be air-blown with catalysts such as ferric chloride and the like. The asphalt can be a conventional roofing flux asphalt or a paving-grade asphalt, as well as other types of asphalts, including specialty asphalts such as water-proofing asphalts, battery compounds, and sealers. Blends of different kinds of asphalt can also be used.

28. The polymer added to the asphalt according to the present invention can be any polymer capable of melting and forming a skim of sufficient viscosity on the upper surface of the molten asphalt to reduce fuming from the kettle. The polymer should have a relative density lower than that of the asphalt so that it rises to the upper surface of a kettle of the molten asphalt, and should be miscible and compatible with the asphalt. Such polymer may be blended with asphalt as described in the referenced patents.

29. Exemplary polymers that may be used include polyolefin polymers such as polypropylene, ethylene-propylene copolymers, and butylene copolymers; ethylene-vinylacetate copolymers; copolymers of acrylates and methacrylates, such as butyl, propyl, ethyl, or methyl acrylate or methacrylate copolymerized with ethylene, propylene, or butylene; epoxy-functionalized copolymers such as a terpolymer of ethylene, butyl acrylate and glycidyl methacrylate, available from E. I. duPont de Nemours & Co. (Wilmington, Del.) as Elvaloy® AM; and synthetic rubber such as styrene-butadiene-styrene (SBS), styrene-butadiene rubber (SBR), styrene-ethylene-butylene-styrene (SEBS), or terpolymer made from ethylene-propylene diene monomer (EPDM); and mixtures thereof. Preferably, the polymer is selected from polypropylenes, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers (EVA), ethylene-methyl acrylate copolymers (EMA), synthetic rubbers, and mixtures thereof. Particularly preferred are polypropylenes, ethylene-methyl acrylate copolymers and ethylene-vinyl acetate copolymers. Useful ethylene-vinyl acetate copolymers preferably have a vinyl acetate content from about 5% to about 40% by weight, more preferably from about 9% to about 28% by weight, so that they are suitably soluble in the asphalt. Preferred ethylene-vinyl acetate copolymers include the Elvax® series from duPont, such as Elvax 360 through 750, preferably Elvax 450 or 470. Ethylene-vinyl acetate copolymers are also available from USI Chemicals under the trade names Ultrathene® and Vynathenet®.

30. The skim is preferably viscous enough so that it stays together as a continuous layer to reduce fuming from the vessel. If the viscosity of the skim is too low, fumes from the molten asphalt could break up through holes in the skim and escape from the vessel. In contrast, if the viscosity is too high, the polymer will not easily form a continuous skim over the entire exposed surface of the asphalt, nor redisperse or dissolve easily into the bulk asphalt over time. To provide a preferred viscosity, the added polymer preferably has a melt flow index of from about 4 to about 150 grams/10 minutes, more preferably from about 10 to about 50 grams/10 minutes, and even more preferably from about 10 to about 30 grams/10 minutes. A lower melt flow index generally indicates a more viscous polymer. The melt flow index is measured at 190° C. under a 2.16 kg load according to ASTM D1238 Method B.

31. Although a wide range of polymeric materials are useful in the invention, the polymer selected for use with a particular asphalt should not undesirably modify the properties of the asphalt in the amount added. For example, where the asphalt is intended to be used as a roofing asphalt, it is preferred that both the asphalt without (before addition of) the polymer, and with the polymer, meets the requirements for at least one type of roofing asphalt according to ASTM D312, more particularly ASTM D312-89. Accordingly, it is preferred that the addition of the polymer to the asphalt reduces fuming but does not significantly change the properties of the asphalt. More preferably, the asphalt with the added polymer meets the following ASTM D312 specifications for a Type III roofing asphalt: softening point (by ASTM D36) of 85-96° C.; flash point of 246° C. minimum; penetration (by ASTM D5) at 0° C. of 6 dmm minimum, at 25° C. of 15-35 dmm, and at 46° C. of 90 dmm maximum; ductility (by ASTM D-1 13) at 25° C. of 2.5 cm minimum; and solubility (by ASTM D2042) in trichloroethylene of at least 99%. Preferably the addition of the polymer to the asphalt does not change the softening point of the asphalt by more than about 9° C., more preferably not more than about 3° C., and does not change the penetration of the asphalt by more than about 10 dmm at 25° C.

32. Further, in some instances, the polymer chosen for use with a particular asphalt, and the amount added, may be selected to enhance the physical properties of the resulting composition. For example, the polymer selected for use with cold-flowable paving asphalts may advantageously be selected to enhance the properties of such asphalts, such as their high-temperature performance as measured by, e.g., the Federal Highway Association's pending Strategic Highway Research Program (SHRP) specification. Exemplary polymers for improving asphalt paving properties include ethylene-vinylacetate copolymers, styrene-butadiene-styrene rubber, polypropylene, and ethylene-methylacrylate copolymers.

33. The polymer is typically added to the asphalt in an amount sufficient to reduce the visual opacity of the fumes from the vessel by at least about 25% with respect to the same asphalt without the polymer. The visual opacity of the fumes is a measure of the blockage of natural light by the fumes. The more fumes emitted from the vessel, the higher the visual opacity. Conversely, a reduction in the visual opacity indicates a reduction in the amount of fumes emitted from the vessel. Preferably, the polymer is added in an amount sufficient to reduce the visual opacity of the fumes by at least about 35%, more preferably at least about 50-60%, and even more preferably at least about 70-80%.

34. The reduction in visual opacity of the fumes increases at higher temperatures where fuming is at its worst with conventional asphalt products. Kettles of roofing asphalt are typically heated to temperatures of from about 232° C. to about 288° C. Preferably the added polymer reduces the visual opacity of the fumes by at least about 35% at 260° C., and more preferably at least about 50% at 260° C.

35. Further, the total emissions of benzene soluble suspended particulates from the vessel is typically reduced by at least about 15% over the same asphalt without the polymer. Preferably the total is reduced by at least about 25%, more preferably at least about 40-50%, and even more preferably at least about 60-70%. The total benzene soluble suspended particulate emissions is made up of the small particles of benzene soluble solid materials present in the fumes, so that a reduction in such particulate emissions indicates a reduction in the amount of fumes emitted. Preferably the total suspended particulates emissions is reduced by at least about 25% at 260° C., and more preferably at least about 50% at 260° C.

36. To provide a polymer skim to achieve such reductions in fuming, the concentration of polymer is preferably sufficient to form a skim over the entire exposed surface of the asphalt in the vessel. Preferably, the amount of polymer added is within the range of from about 0.2% to about 6% by weight based on the total weight of the asphalt and polymer. More preferably, from about 0.2% to about 2%, and even more preferably, from about 0.3% to about 1.5% polymer is added based on the total weight of asphalt and polymer. At such levels, the amount of fumes normally emitted from a vessel of the molten asphalt is significantly reduced without any significant modification of the asphalt properties.

37. In a preferred embodiment, the polymer is added to the asphalt in the form of a container having paper sides and a consumable bottom made from a polymer material as described above. Preferably, the consumable container bottom includes an adequate amount of polymer to form the skim as set forth above. However, if necessary, additional polymer (beyond that found in the consumable container bottom) can generally be added to the asphalt in almost any manner to reduce fuming, as set forth in the '276 and '194 patents. The additional polymer can be added to the asphalt before it is transported to the end user, or the polymer can be added to the asphalt by the end user. The end user can add the additional polymer directly to the vessel of molten asphalt. The additional polymer can be added to the asphalt in liquid form or in solid form, e.g., in the form of pellets, granules, flakes, particles, powders, or other formed shapes (hereinafter collectively referred to as “pellets”). Addition may also come in any of the above forms encapsulated or otherwise contained in a polymeric bag, which can be added easily to any asphalt vessel. When the polymeric bag is added to molten asphalt, the bag melts releasing the contained polymer and the polymeric material of the bag.

38. Preferably, the consumable bottom is made from polymer, or a mixture of polymer and asphalt. Preferred such polymer/asphalt mixtures may contain from about 20% to about 100% by weight polymer and from about 0% to about 80% asphalt. Preferably, such mixtures contain from about 40% to about 100% polymer. More preferably, such mixtures comprise from about 0% to about 60% asphalt and from about 40% to about 100% polypropylene.

39. Suitable polymer/asphalt composite bottoms may be formed by co-extruding the asphalt and polymer through a heated extruder wherein the materials are heated above their softening points and blended together, such as occurs in conventional extruders, and then forming the moldable mixture into bottoms. Preferably the bottom is formed as an integral or unitary structure by a molding process such as injection molding, blow molding, or rotation molding, or may be formed by any other means, such as compression molding, stamping, or any other form of molding. A preferred manner of direct injection molding is described in U.S. Pat. No. 5,985,200, which incorporated herein by reference. Alternatively, flanges, rings, and other details can be added to the bottom in secondary known processes. Furthermore, the bottoms may be made by any known method, such as by extruding a sheet and vacuum forming the sheet to the desired bottom shape. Accordingly, the polymers used for providing the skim and the asphalts preferably have melting points and viscosities that are suitable for such processes, including coextrusion. Preferred asphalts generally have a ring and ball softening point higher than about 90° C. measured according to ASTM D36. It is not necessary that the asphalt component of the bottoms be the same as the molten asphalt in the vessel. Suitable asphalts include air-blown roofing flux and air-blown paving-grade asphalt in the range of from AC-2 to AC-50, more preferably AC-10 or AC-20.

40. Optionally, non-polymeric chemical modifiers and additives, such as a synthetic wax, may be added to the bottom composition. This feature advantageously permits the use of one or a few standard asphalts to fill the vessel, with the desired chemical additives for optimizing the asphalt for the intended application being added to the asphalt via the bottom.

41. Additionally, one or more filler materials, such as crushed stone, glass fibers, talc, calcium carbonate, or silica, may be added to the bottom formulation if desired. However, such filler materials would be undesirable in some end uses of the asphalt and are not generally preferred. Accordingly, it is to be understood that the filler materials are to be ignored when calculating the percentages of other specified materials in the asphalt; thus, the weight percentages of ingredients given herein are based on total weights of the materials or compositions exclusive of any filler or the like present in the material or composition.

42. Polymer bottoms or asphalt/polymer composite bottoms may be of any conveniently formed size, thickness, and geometric configuration that will exhibit suitable melting and/or dissolution rates, as well as provide the strength, impact and cold flow properties useful for such a package. Preferred shapes are illustrated in the Figures, but one skilled in the art appreciates that minor variations in the bottoms may be made without departing from the intent of the present invention. Furthermore, a polymer top may be used in combination with, or as a substitute for, the bottoms described herein.

43. Referring now to the Figures, there is illustrated in FIG. 1 a prior art container 10, including cylindrical sides 12 made of paper or cardboard, and a steel bottom 14 pressed thereon. As noted above, at a jobsite, the paper 12 and bottom 14 are removed and discarded, and the remaining asphalt is thrown into a kettle.

44. In preferred embodiments of a consumable container for asphalt shown in the drawings, FIG. 2 illustrates a preferred improved container 210, including cylindrical sides 212, preferably made from paper, and a consumable bottom 214 pressed thereon. The present invention preferably includes a string 218 provided in the container adjacent the sides 212 as described further below. The string 218 is pulled to tear the sides 212, and therefore eliminates the need for a knife to cut the paper for removal, as commonly used with prior art containers, to cut the sides 212 at the jobsite to remove the sides 212. Furthermore, a series of perforations 216 may be formed in the sides 212 adjacent the string 218. One skilled in the art appreciates the perforations 216 may be formed in the sides 212 prior to pouring the asphalt, and therefore the perforations 216 are preferably not formed through the side, so molten asphalt will not flow therethrough when poured into the container. Alternatively, the perforations 216 may be a score line formed in the side 212. Furthermore, the perforations could be formed after the asphalt solidifies, so the perforations may penetrate the side and be placed adjacent the string after the asphalt is poured. In an alternative embodiment, the perforations 216 are formed in the sides 212, so the string 218 is not required, as the sides 212 may be torn at the perforations 216 by hand. The perforations 216 may thus be a series of short perforations, or a continuous score along a portion of the side 212, or the entire length thereof. The perforations 216 may be formed using a knife, roller, laser, waterjet, heat source, or any other known means to locally weaken the side 212.

45. The string 218 is preferably inserted inside the container before pouring asphalt into the container, adjacent the side at the perforation and preferably trapped at the bottom of the container by the consumable bottom. At the jobsite, a worker pulls the string 218 to tear the sides 212 at the perforations 216 (if provided). The string can be taped to the interior of the container with a tape that is consumable in the asphalt, or adhered to the side with glue, or held by other known means prior to pouring the asphalt. Furthermore, it is preferred that a known release agent is applied to the inside of the sides 212 to facilitate removal from the asphalt at the jobsite, or a polymer bag may be used within the walls of a paper side. Alternatively, the sides 212 may be made from a polymer, either consumable or nonconsumable, instead of the paper. As such, the nonconsumable polymer sides would be removed at the jobsite and disposed of, while the consumable sides would be thrown into the vessel with the asphalt. Such sides could be formed from a sheet of polymer and welded or glued into a cylindrical shape.

46. Variations of the polymer bottom 214, shown in FIGS. 2 and 3, as shown in FIG. 4. The bottom 414 of FIG. 4 is described in assembly with the sides 212 shown in FIG. 2 for simplicity. The Bottom 414 includes a pair of annular rings 420, 440 projecting upwardly therefrom, and preferably molded integrally therewith. The bottom of the container sides 212 (ref FIG. 2) is sandwiched between the rings 420, 440 to form a container 210 and prevent leakage when molten asphalt is poured into the container 210. In the illustrated embodiment, the container is generally cylindrical in shape, having an open end and a closed end. However, the container may be any other convenient shape, such as a rectangular solid shape. Although shown with the interior ring 420 taller than the outer ring 440, the relative heights may be identical or reversed from that illustrated. One skilled in the art appreciates the bottom 214 may have perforations formed therein, thereby enabling a workman to rip a flange (e.g. 440) from the bottom 414 to facilitate removal of the paper side 212.

47. Although rectangular solid shapes may provide efficiencies in shipping and storing, these advantages may be outweighed by the advantage of providing containers separable by a substantial distance during the pouring process in order to facilitate rapid cooling. As Preferably the bottom 414 includes a pair of rings (not shown) projecting downwardly therefrom and may include a consumable or disposable lid (not shown), as described in the '276 patent. Similarly, the bottom 214 can include additional features, such as handholds (not shown), which can be molded into the container to facilitate handling, hooks for handling, product information, or any other useful features.

48. A further alternate embodiment of a consumable bottom is shown in FIG. 5. Referring to FIG. 5, the bottom 514 includes a single annular ring 520 projecting upwardly therefrom. In the illustrated embodiment, the ring 520 is press fit in to the inside of the side 512, but could similarly be press fit onto the outside of the side 512.

49. Further alternative embodiments are shown in FIGS. 6-10, including a bottom 614 made from a pair of cup-shaped discs 620, 630, each of which includes an upstanding flange 622, 632, respectively. A larger disc 630 is pressed on the outside of the sides 212, then a smaller of the discs 620, is installed inside the sides 212, sandwiching the sides 212 between the flanges 622, 632. Alternatively, the order of assembly may be reversed. Preferably, the smaller disc 620 includes a hole in the bottom thereof (not shown), so when the asphalt is poured into the container, it contacts the bottom disc 630 and secures the bottom 630 when the asphalt solidifies in the package 210. The flanges 622, 632 preferably extend substantially perpendicular to the discs 620, 630, but preferably also include a slight angle and/or taper to facilitate installation to the sides 212 over or onto the flanges 622, 632 (i.e. the smaller disc 620 may include a flange 622 with a smaller outside diameter at the top and larger diameter at the bottom).

50.FIG. 8 illustrates a cross-section of a further embodiment, similar to that described above with reference to FIG. 7, but the sides 812 include a horizontal flange 814 that is trapped between a pair of discs 820, 830. In the shown embodiment, the bottom disc 830 is substantially flat and may include an optional circumferential flange 832 on the top surface thereof. A second disc 820 traps the horizontal flange 814 between itself and the bottom disc 830. Preferably, the second disc 820 is substantially cup-shaped, with an upstanding flange 822, but could be made flat. Preferably, the second disk 820 includes a hole 824 through which molten asphalt engages the bottom disc 830- as described above with reference to FIGS. 6 and 7. Preferably, the flange 832 has a press fit to the hole 824, or alternatively, a press fit to a flange (not shown) formed on the bottom of the second disc 820, thereby securing the discs 820, 830.

51. As illustrated in FIGS. 9 and 10, the horizontal flange 814 is created by forming a series of cuts 818, 818′ (or more preferably notches, in the shape of a “V”, not shown) in the lower end of the side 812, forming a series of tabs 819. The tabs are then bent approximately 90 degrees from the side 812 to form the flange 814. In a further alternative embodiment, the sides 812 are formed as shown in FIG. 10 and set upon a single disc 830, and the asphalt is poured to form a package (without the second disc 820). In this alternative embodiment, a cup-shaped fixture (not shown) is provided to hold the package while the asphalt is poured to prevent any leakage.

52. The invention will now be further illustrated by reference to the following examples.

EXAMPLE 1

53. Testing was conducted to measure the ability of a minor amount of asphalt/polymer composite incorporated in a conventionally packaged asphalt product to reduce fuming from a kettle of the molten asphalt during remelting. In this test, fuming of a standard BURA Type III asphalt (Amoco roofer's flux asphalt air-blown to a softening point of from about 85° C. (185° F.) to about 96.1° C. (205° F.)), packaged in a conventional paper container, was tested both with the amount of polymer from a consumable container bottom (“low-fuming product”), and without the added polymer (“standard product”).

54. The polymer added to the low-fuming product was prepared by forming a mixture of asphalt air-blown to a softening point of about 143° C. (290° F.), polypropylene (Montel 6301 or Solvay Fortilene 12 melt flow index homopolymer), and ethylene-vinylacetate copolymer (Elvax 450) at a ratio of 60:30:10 by weight. Such polymer may be formed into a consumable bottom according to the present invention.

55. The equipment used for the testing included a 625-liter roofer's kettle heated by a propane burner. In the testing, the low-fuming product and the standard product were separately added to the kettle and melted to fill the kettle. The products were each tested at temperatures of 260° C. and 288° C. (500° F. and 550° F.), and the low-fuming products were tested at polymer concentrations ranging from 0.16 to 0.96 percent by weight of the total asphalt and polymer in the composition. To simulate actual usage conditions, 75.7 liters of molten product were drained from the kettle every 20 minutes and replaced by additional product added to the kettle. The testing was conducted outdoors, with the area around the kettle being surrounded to block the wind. The fumes emitted from the kettle were measured for visual opacity, and total suspended benzene soluble particulates as described below.

56. The test for visual opacity was performed in accordance with 40 C.F.R., Part 60, Appendix A, EPA Method 9, entitled “Visual Determination of the Opacity of Emission from Stationary Sources.” A certified reader of opacity recorded the visual opacity every 15 seconds for two hours. The reader observed the fumes from the kettle and determined a percent opacity or blockage of the natural light. A low opacity indicates very little fumes, whereas a high opacity indicates a lot of fumes coming off the kettle. The results of the visual opacity readings are shown below in Table I, where the percent opacity is the average over the two-hour test: TABLE I Visual Opacity Weight % Polymer Temperature (° C.) Opacity (%) 0 (standard) 260 18 0 (standard) 288 19.5 0.16 260 16.6 0.16 288 26.9 0.32 260 11.4 0.32 288 16.9 0.64 260 10.1 0.64 288 9.4 0.96 260 5.1 0.96 288 5.3

57. The results of the visual opacity readings show that the low-fuming product had visibly lower fuming from the kettle than the standard product at polymer concentrations of 0.32 weight percent and above. Further, it was observed that at polymer loadings of 0.32 percent and above, the polymer of the low-fuming product formed a skim on substantially the entire upper surface of the molten asphalt.

58. The test for total benzene soluble suspended particulates was performed in accordance with the “Standard Operating Procedure: Benzene Solubles Method for Asphalt Institute Round Robin Study” which is a modified version of National Institute of Occupational Safety and Health (NIOSH) method 5023, 3rd edition. Two high-volume (Hi-Vol) TSP (total suspended particulates) samplers were elevated to position the sample inlets slightly above the kettle rim near the kettle opening. Each of the samplers pulled a stream of fumes from the kettle through a pre-weighed 1 ft² filter. Each sampler was operated for 2 hours. Thereafter, the filter elements were removed, covered with benzene (HPLC grade with evaporation residue of no greater than 0.0005%) and left for at least one hour. The benzene extract was then filtered in a Millipore Miliflex SR disposable filter under nitrogen pressure (approximately 7-10 psi). The benzene was then concentrated in a heater block at 85° C., transferred to pre-weighed cups, and placed in a vacuum oven at ambient temperature and 20-25 mm Hg vacuum overnight. The cups were then weighed to determine the amount of benzene soluble particulates. The results of the total benzene soluble suspended particulates measurements are shown below in Table II. The measurements are given in micrograms of particulates per standard cubic meter (scm) of fumes at standard conditions of one atmosphere pressure and 20° C. TABLE II Total Benzene Soluble Suspended Particulates Benzene Soluble Particulates μg/SCM Weight % Polymer Temperature (° C.) Sampler 1 Sampler 2 0 (standard) 260 943 1626 0 (standard) 288 2463 3284 0.16 260 599 1663 0.16 288 3139 5187 0.32 260 — — 0.32 288 — — 0.64 260 304 615 0.64 288 236 1465 0.96 260 443 553 0.96 288 301 1530

59. These results, like the visual opacity results, show that the low-fuming product reduced the amount of fumes from the kettle compared to the standard product. The benzene soluble particulates were consistently lower for the low-fuming product versus the standard product at polymer levels greater than 0.32%.

EXAMPLE 2

60. The benzene soluble particulates emitted were measured for 16 additional samples of standard product and low fuming product having 0.32 weight percent polymer. The results are shown below in Table III. TABLE III Total Benzene Soluble Suspended Particulates Benzene Soluble Weight % Polymer Temperature Particulates (μg/SCM) 0 260 2377 0 260 3306 0 260 1861 0 260 2132 0 260 2519 0 260 1652 0 260 5833 0 260 2702 0 288 3292 0 288 3756 0 288 5633 0 288 3507 0 288 5809 0 288 4103 0 288 18854 0 288 12808 0.32 260 768 0.32 260 687 0.32 260 38 0.32 260 535 0.32 260 116 0.32 260 129 0.32 260 106 0.32 260 194 0.32 288 415 0.32 288 636 0.32 288 387 0.32 288 522 0.32 288 165 0.32 288 429 0.32 288 118 0.32 288 485

61. These results show that the benzene soluble particulates are also lower at 0.32% polymer than for the standard product.

EXAMPLE 3

62. A supply of molten asphalt is transported in a tanker truck to an end user, who places a quantity in a roofer's kettle for heating to a temperature suitable for application as roofing asphalt. The end user may be supplied with containers having a consumable bottom. The end user removes the paper side from the container, as described above, by pulling the string to tear the sidewalls at the perforation, and discards the paper and string. To simulate these conditions, asphalt and the amount of polymer for the consumable bottom are melted. The polymer forms a skim on the surface of the molten asphalt that reduces fuming from the kettle.

EXAMPLE 4

63. A consumable container for asphalt was formed according to the following low-fuming method. Amoco AC-20 asphalt air-blown to a softening point of 121° C., polypropylene (Profax 6301), and ethylene-vinyl acetate copolymer (Elvax 450) were formed in a twin screw extruder at a ratio of 60:30:10 by weight. The screw temperature was set at 177° C. The mixture had a melt flow index of about 46.6 grams/10 minutes. The mixture was tough and impact-resistant, having an unnotched Izod impact strength of 4.5 joules, a tensile strength of 95.5 kg/cm2 at 22° C., a tensile strength of 25.3 kg/cm2 at 93° C., and a tensile modulus of 336 kg/cm2 at 93° C.

64. A container was filled with a BURA Type III roofing asphalt at a temperature of 166° C. The asphalt package (the assembled container and the asphalt held in the container) weighed 45 kg when full. The asphalt package met the requirements for Type III roofing asphalt according to ASTM D312.

65. The container bottom can be melted right along with the asphalt held in the container without significantly changing the properties of the asphalt. The softening point of the asphalt alone was 89° C., and the softening point of the combined asphalt and polymer amount for a container bottom was 95° C. The asphalt alone had a penetration of 19 dmm at 25° C., and the combined asphalt and polymer for a container bottom had a penetration of 17 dmm at 25° C.

EXAMPLE 5

66. Montel Polypropylene 6301 and coating asphalt having a softening point of 230° F. (110° C.) were pelletized in a twin screw extruder at a ratio of 30:70 by weight. The screw temperature was set at 350° F. (177° C.). Pellets were added to a body of molten BURA Type III asphalt to simulate the amount of polymer from a consumable bottom. The weight of the polymer was 4 percent of the total weight of the asphalt and polymer. The properties of the asphalt before and after addition of the polymer were measured, with the results given in the table below along with the ASTM D312 Type III specifications for comparison. TABLE IV Effects of the Addition of Polymer to Molten Asphalt Asphalt + BURA Type III 4 wt. % ASTM D312 Property Asphalt Alone Polymer Type III spec. Softening pt. 192° F. (89° C.) 204° F. (96° C.) 185-205° F. (85-96° C.) Penetration @  19 dmm  16 dmm  15-35 dmm 77° F., 100 g Penetration @ 115° F., 50 g  37 dmm  29 dmm  90 dmm max. Viscosity @ 140 cps 254 cps — 400° F. Viscosity @  91 cps 150 cps — 425° F. Viscosity @  64 cps  95 cps — 450° F.

67. It can be seen that the addition of the polymer to the asphalt had only a slight effect on the properties of the asphalt, with the most pronounced change being the increased viscosity.

EXAMPLE 6

68. Montel Polypropylene 6301, a highly blown asphalt, and BURA Type III asphalt were pelletized in a twin screw extruder at a ratio of 40:20:40 by weight. The highly blown asphalt was a Trumbull material from a propane-washed asphalt blend having been blown to a softening point of 300° F. (149° C.). The screw temperature was set at 350° F. (177° C.). The pellets may be used to injection-mold a container bottom having the features described herein. An asphalt package including the container and the asphalt therein weighed 10 lbs. when full. Asphalt and a polymer material container simulating such a container were lowered in a wire basket into a roofer's asphalt kettle containing molten asphalt at 475° F. (246° C.). Without stirring, the package was completely dissolved by natural convection without any visible trace within 15 minutes. The properties of the asphalt before and after addition of the containers were measured, with the results given in the table below in comparison with the ASTM D312 Type III specifications. TABLE V Effects of the Addition of Asphalt- Filled, Molded Containers to Molten Asphalt Asphalt + BURA Type III 4 wt. % ASTM D312 Property Asphalt Alone container Type III spec. Softening pt. 192° F. (89° C.) 207° F. (97° C.) 185-205° F. (85-96° C.) Penetration @  19 dmm  17 dmm  15-35 dmm 77° F., 100 g Penetration @ 115° F., 50 g  37 dmm  29 dmm  90 dmm max. Viscosity @ 140 cps 254 cps — 400° F. Viscosity @  91 cps 150 cps — 425° F. Viscosity @  64 cps  95 cps — 450° F.

69. The results are similar to those in Example 5. The softening point of the asphalt having the melted container was slightly above the Type III specification.

70. Breakage means, such as described in my copending application Ser. No. 09/169,964 may be inserted inside the container walls to provide a breakage means or other feature in the asphalt container. Such breakage means may be inserted as a rod or bar adjacent the sidewall, in place of the string illustrated in the figures, and thereby provide a means for tearing the sidewall. The same breakage means provides an indentation in the asphalt block and therefore facilitates breakage of the block, while also providing a further source of polymer in the kettle.

71. In a further alternative embodiment, the principles of this invention are achieved using a container with conventional paper sides and a metal bottom, but a cylindrical polymer slug is inserted into the container prior to pouring the asphalt. The slug preferably isolates the asphalt from the metal bottom and provides the asphalt content for the low fuming characteristics described herein. Furthermore, such a container may use the string and/or scored container sides as described above.

72. Although the invention has been described in detail in reference to preferred feature and embodiments, appropriate modifications will be apparent to the artisan. Thus, the invention is intended not to be limited by the foregoing description, but to be defined by the appended claims and their equivalents. 

What is claimed is:
 1. A container for asphalt, comprising: a sidewall; a bottom assembled to the sidewall to form the container for holding the asphalt in the container, the bottom thereafter being melted with the asphalt without adversely affecting the asphalt properties.
 2. A container according to claim 1 , wherein said sidewall comprises a cylinder with a pair of open ends and the bottom is attached to a first one of the open ends.
 3. A container according to claim 2 , wherein said bottom comprises a disc having a top surface with an annular flange extending substantially perpendicular thereto, said flange having an interference fit to the open end of the sidewall.
 4. A container according to claim 3 , wherein said annular flange has an interference fit to an interior wall of the open end of the sidewall.
 5. A container according to claim 3 , wherein said bottom comprises a second annular flange extending substantially parallel to the first flange, said open end of the sidewall being inserted between said flanges.
 6. A container according to claim 3 , wherein said bottom comprises a second annular flange extending substantially perpendicular to the disc, substantially concentric with the first annular flange, one of said first and second flanges fitting to an inside surface of the open end of the sidewall, and the second of the flanges fitting to an exterior outside surface of the open end of the sidewall.
 7. A container according to claim 3 , wherein said bottom comprises a second disc having a second annular flange extending substantially perpendicular to the second disc, the first annular flange fitting to an internal surface of the first open end and the second flange fitting to an outside surface of the open end of the sidewall.
 8. A container according to claim 7 , wherein the first disc has a hole provided therein for allowing the asphalt to contact the second disc when the asphalt is poured into the container.
 9. A container according to claim 1 , wherein said sidewall comprises a cylinder with a pair of open ends, a first end having a plurality of notches in the sidewall to form a plurality of tabs, the tabs bent with respect to the sidewall to form a radial flange, and the bottom comprises a pair of discs, one of said discs being assembled to a bottom surface of the radial flange and the second disc being assembled to a top surface of the radial flange.
 10. A container according to claim 9 , wherein the second disc comprises an annular flange for installation to an interior surface of the sidewall at the first end of the sidewall adjacent the radial flange.
 11. A container according to claim 10 , wherein the second disc has a hole formed therein for asphalt to flow therethrough to engage the first disc when pored into the container.
 12. A container according to claim 11 , wherein the first disc comprises an annular flange for installation to an exterior surface of the sidewall at the first end of the sidewall adjacent the radial flange.
 13. A container according to claim 12 , wherein the first disc comprises a second annular flange for engagement with the second disc.
 14. A container according to claim 3 , wherein the asphalt and bottom are placed into a vessel and heated to melt the asphalt and the bottom.
 15. A container according to claim 14 , wherein the sidewall comprise a plurality of perforations formed longitudinally thereon for tearing the sidewall to remove the sidewall from the asphalt.
 16. A container according to claim 15 , further comprising a string provided in the container adjacent the sidewall perforations for tearing the sidewall after the asphalt is poured into the container.
 17. A container according to claim 16 , wherein the sidewall is made from a paper material and discarded prior to melting the asphalt and bottom.
 18. A container according to claim 2 , wherein the sidewall is made from a polymer material.
 19. A container according to claim 14 , further comprising a string provided in the container adjacent the sidewall perforations for tearing the sidewall after the asphalt is poured into the container.
 20. A container according to claim 1 , wherein the asphalt and bottom are placed into a vessel and heated to melt the asphalt and bottom, the molten asphalt normally emitting fumes from the vessel, and the consumable bottom comprises about 0.2 weight percent to about 6 weight percent of a polymer added to the asphalt to reduce the visual opacity of the fumes by at least about 25% with respect to the same asphalt without the consumable bottom.
 21. A container according to claim 20 , wherein the polymer from the bottom forms a skim on the upper surface of the molten asphalt.
 22. A container according to claim 21 , wherein the polymer has a melt flow index of from about 4 grams/10 minutes to about 150 grams/10 minutes.
 23. A container according to claim 22 , wherein the bottom is made from a material comprising from about 0 weight percent to about 80 weight percent of an asphalt and from about 20 weight percent to about 100 weight percent of the polymer.
 24. A container according to claim 23 , wherein both the asphalt without the polymer and the asphalt with the added polymer from the bottom meet the requirements for at least one type of roofing asphalt according to ASTM D312.
 25. A container according to claim 24 , wherein the addition of the polymer to the molten asphalt neither changes the softening point of the asphalt by more than about 9° C. nor changes the penetration of the asphalt by more than about 10 dmm at 25° C.
 26. A container according to claim 25 , wherein the polymer is selected from the group consisting of polypropylene, ethylene-vinyl acetate copolymer having a vinyl acetate content of from about 5 weight percent to about 40 weight percent, ethylene-methyl acrylate copolymers, rubber, and mixtures thereof.
 27. A container according to claim 19 , wherein the asphalt and bottom are placed into a vessel and heated to melt the asphalt and bottom, the molten asphalt normally emitting fumes from the vessel, and the consumable bottom comprises about 0.2 weight percent to about 6 weight percent of a polymer added to the asphalt to reduce the total emissions of benzene soluble suspended particulates by at least about 15% over the same asphalt without the polymer.
 28. A container according to claim 27 , wherein the added polymer from the bottom forms a skim on the upper surface of the molten asphalt.
 29. A container according to claim 3 , wherein said sidewall is melted with the bottom and asphalt without adversely affecting the asphalt properties.
 30. A container according to claim 2 , wherein said bottom comprises a first disc having a top surface and said sidewall comprises a plurality of tabs extending therefrom, a bottom surface of said tabs positioned upon said top surface of said first disc.
 31. A container according to claim 31 , further comprising a second disc having a bottom surface, said bottom surface positioned upon a top surface of said tabs.
 32. A container according to claim 31 , further comprising a flange provided on each of said discs, each of said flanges mutually engaging the other of said flanges to capture said flanges between the discs.
 33. A method of asphalt production, comprising: forming a sidewall; forming a consumable bottom; attaching the bottom to the sidewall to form a container; pouring molten asphalt into the container and solidifying the asphalt in the container; and melting the solidified asphalt and bottom to form a molten mixture of the asphalt and bottom.
 34. A method according to claim 33 , further comprising the steps of: forming a plurality of longitudinal perforations in the sidewall; providing a string in the container adjacent the perforations; pulling the string to tear the sidewall; and removing the sidewall prior to melting the solidified asphalt.
 35. A method according to claim 33 , wherein the container comprises a cylinder having an end closed by the bottom.
 36. A method according to claim 35 , wherein the bottom has a flange with an interference fit to the end of the cylinder.
 37. A method according to claim 33 , wherein the step of melting the asphalt and bottom comprises placing the asphalt and bottom into a vessel and heated to melt the asphalt and bottom, the molten asphalt normally emitting fumes from the vessel, the bottom made from a polymer which comprises about 0.2 weight percent to about 6 weight percent of a polymer to the asphalt to reduce the visual opacity of the fumes by at least about 25% with respect to the same asphalt without the polymer.
 38. A method according to claim 37 , wherein the added polymer forms a skim on the upper surface of the molten asphalt.
 39. A method according to claim 38 , wherein the polymer has a melt flow index of from about 4 grams/10 minutes to about 150 grams/10 minutes.
 40. A method according to claim 39 , wherein the polymer is added in the form of a consumable container bottom for closing the end of the container to hold the amount of unmelted asphalt, the bottom made from a material comprising from about 40 weight percent to about 90 weight percent of an asphalt and from about 10 weight percent to about 60 weight percent of the polymer.
 41. A method according to claim 40 , wherein both the asphalt without the polymer and the asphalt with the added polymer meet the requirements for at least one type of roofing asphalt according to ASTM D312.
 42. A method according to claim 41 , wherein the addition of the polymer to the molten asphalt neither changes the softening point of the asphalt by more than about 9° C. nor changes the penetration of the asphalt by more than about 10 dmm at 25° C.
 43. A method according to claim 42 , wherein the polymer is selected from the group consisting of polypropylene, ethylene-vinyl acetate copolymer having a vinyl acetate content of from about 5 weight percent to about 40 weight percent, ethylene-methyl acrylate copolymers, rubber, and mixtures thereof.
 44. A method according to claim 33 , wherein the step of melting the asphalt and bottom comprises placing the asphalt and bottom into a vessel and heated to melt the asphalt and bottom, the molten asphalt normally emitting fumes from the vessel, and the bottom comprises about 0.2 weight percent to about 6 weight percent of a polymer to the asphalt to reduce the total emissions of benzene soluble suspended particulates by at least about 15% over the same asphalt without the polymer from the bottom.
 45. A method according to claim 44 , wherein the added polymer forms a skim on the upper surface of the molten asphalt.
 46. A method according to claim 45 , wherein the polymer has a melt flow index of from about 4 grams/10 minutes to about 150 grams/10 minutes.
 47. A method according to claim 43 , wherein the step of melting the asphalt and bottom comprises placing the asphalt and bottom into a vessel and heated to melt the asphalt and bottom, the molten asphalt normally emitting fumes from the vessel, and the bottom comprises about 0.2 weight percent to about 6 weight percent of a polymer to the asphalt to reduce the visual opacity of the fumes by at least about 25% with respect to the same asphalt without the polymer.
 48. A method according to claim 47 , further comprising the steps of: forming a plurality of longitudinal perforations in the sidewall; providing a string in the container adjacent the perforations; pulling the string to tear the sidewall; and removing the sidewall prior to melting the solidified asphalt.
 49. A method according to claim 47 , further comprising the steps of: providing a string in the container adjacent the sidewall; pulling the string to tear the sidewall; and removing the sidewall prior to melting the solidified asphalt. 